I have a problem that my mechanic just can't seem to fix. First of all a bit of a rundown on the bike; I bought it used from a automotive mechanic when it had about 19K km on it. It came with a set of aftermarket cans on it and everything else was box-stock. I added a Rottweiler SAS removal kit, removed the secondary butterflies, keeping the shafts in and installed a MotoHooligan airbox in the time that I've had it (added in that order) and the thing rang fine. I then made an appointment to have the bike dyno'd by a reputable vendor. Shortly after making the appointment, I had the bike die on my on a short commuter ride. It felt like it ran out of fuel. I turned off the ignition and was able to restart it and carry on. It did it two more times in that ride and I was able to get it going again, following the same procedure. I then contacted thr dyno vendor to report the problem and asked if it was still worth bringing the bike in and they said yes, as they could at least see the error code if it did come up again. The bike did do the same thing on the dyno and gave a #2 cylinder coil pack error code. The mechanic also got a shock off the bike. They pulled the sparkplugs and reported that the electrode on #2 plug was almost completely gone and that it must have grounded out to the bike (they also reported that both plugs had oil residue on them but didn't think much of it as the LC8 has a tendency to burn a bit of oil. We replaced both sparkplugs and they were able to carry out the work. I rode the bike a few times after that and noted the improved throttle and extra oomph. Then the problem returned. It seems to happen at 4-5000 rpm and really feels like a fueling issue. I brought the bike to the shop, they saw the same code and claimed to have found a problem with the #2 cylinder coil pack, which they repaired. I came to pick up the bike, turned on to the main drag, and the bike died with the same symptom. I've since been back to the shop four times to pick it up only to return the bike with the same problem. We've replaced the fuel filters, the fuel pump, they reflashed my ECU (loosing my dyno tune in the process), and tried a different battery, as the one that I put in last year was outputting about a volt lower than spec in various running conditions. Each subsequent time that the bike's gone back, they've taken it for a test ride and it runs fine, only for me to pick it up and have the problem rear its ugly head again. I tried to isolate the problem to a cold-running engine and a hot one but the only real consistent condition is that it happens above 4000RPM and can be remedied by switching off the ignition and turning it back on again, sometimes with a 5-10 minute wait at the side of the road, although I still can't say that it's heat-related as it has stalled while warming up on the side stand at idle as well as when I rev it to the 4000-5000rpm range after a brief warm-up.

I'm at a loss as to what it can be and my mechanic also seems to be stumped. They're now talking about replacing the ECU, which is a $675CDN, non-refundable roll of the dice. Any light that you might be able to shed on the problem would be immeasurably appreciated! I've been over two months without a ride and we've been having one of the driest Summers in recent memory and am getting angry and depressed at the same time over it.

Simple thing I’m not seeing is a coil pack swap between #1 & #2. If it fails again with an error and it’s followed the same coil, just replace it. You don’t know that the repair they did on the coil is good.

I would have through any good mechanic would have swapped the coil over with number 1.

We have seen a few funny thing over the years & one of them is the engine loom been rubbed through or pinched when the air box has been removed & reinstalled, double check the loom around the top of the motor & make sure it has not rubbed through anywhere or pinched, unclip the loom & examine it closely, any signs of been pinched un-tape the loop to inspect. If the primary ignition wire has been pitched to earth it can damage the ECU.

Next thing is the big grey connector, we have seen corrosion in this connector many times.

I personally would run new wires & pins at both ends from number 2 coil directly to the engine ECU before I replaced the ECU.

Your bike was in open loop mode when the fault first appeared ? (ie: no feedback from the O2 sensors).

Can you get a pic of the faulty plugs ?

The electrical shock the mechanic reported is an interesting one. He has become apart of the high voltage circuit (the orange or white/orange wires in the schematic below). A shorted out plug won't make him apart of this path (secondary winding). Only if he disconnected and stuck his finger in it... or a faulty stick.

Why oh why won't KTM use standard symbols.

Just a theory: Has your bike had any modifications that use the black wire becoming out of pin 7 of the ECU ?. This black wire looks like a floating ground controlled by the ECU. This wire grounds (what looks like) a sensor in the coil stick. A working stick won't produce a shock (as mentioned), so how is mechanic becoming apart of the high voltage circuit ?. Well, the sensor is grounded by the black wire, and a few systems use this wire. I'm figuring you could be getting the shock off this ground via sensors/devices that use this ground. The orange wire going into the stick is 12V (low resistance, so should in theory "short out" the shock via the battery - assuming battery is good and is connected properly - to the ground and mechanic won't feel it.. and could rule out the orange wire).

Not sure how the ECU is pulsing the stick (relay ?), but if a high voltage pulse is going to the sensor input of the ECU, then this will kill the ECU - completely dead (unless KTM has thought of this faulty stick scenario).

Does your bike have an immobiliser ?

How did they repair the stick coil ?. This is a plastic conformed unit and not serviceable.

As Kev said. There are some dodgey looking pinch points with the loom getting pushed up against very hot surfaces. I'll hate to see what happens when these conductors start oxidising and going high resistance !

- I don't think that the bike was in open loop mode when the fault first appeared, as it first happened before the dyno-tune and to the best of my knowledge, the previous owner hadn't played with the bike at all, other than to install the aftermarket cans.

- No pic of plugs available

- Don't know if my bike has an immobiliser (I know, I should know these things...)

So this is what happens when a backyard mechanic starts tinkering without really knowing what he's doing and then engages a community who clearly knows more about these things than me!

I believe that I removed the secondary butterflies when I installed the SAS. I did not update the map though. However, it ran fine after that. The problem started occurring after I installed the airbox but it initially happened so infrequently that I didn't chalk it up to any of the what I considered to be minor tweaks. There doesn't seem to be any common factors other than the rev range. It can occur shortly after setting off on a ride or an hour into it. When it's running like it's supposed to, Ive tried deliberately running it in the problematic rev range and also tried running below or above that and it seems fine, until it's not anymore.

When I do go into fail mode between 4-5000RPM, the engine will just stop running, like it's run out of fuel. It doesn't feel like a dropped cylinder and no amount of effort in trying to "power through" the problematic range when I feel it stalling out will save it. I have had the occasional pop or backfire and can sort of feel the engine running a bit rough before I go to full fail mode.

Dave, I'm loosing net access for a week. Cursory response. 4500? 4800?RPM is a cross over range between closed and open loop. Kev or others can expand on that. Could be faulty sensors or modifications confusing the ECU ?. Injecting wrong quantities of fuel ? Did you do a 15min reset after can, airbox and flies mod ?. I think at this stage you need to start measuring sensor values. Do you have TuneECU setup ?. If you plugs are burnt out, I would be worried about cylinder and valves.

So an update on my bike; after having been in the shop for over three months, the owner of the KTM-authorized dealership sent me an email saying that he's run out of ideas and has officially given up on it! They suggested bringing the bike back to stock condition but the mods that I did (as listed earlier in this post) are all very basic and have been done by countless other owners will no ill effect. I'm now left with having to find another mechanic and start basically from scratch. I will convey the suggested possible solutions that a few of you have given me and hope for the best but I have definitely ruled out another KTM purchase, until KTM Canada improves their quality of service and support to their dealers. So frustrated...

I'm onto the same route as 'limeyduffa' - soon it's nescessary to try out eVerytHinG...

I have the 990 2010 as well.
During the hot period in July 2015, the idle went away... just like that, suddenly. It happened a few times during 1 week, and when thinking about it I remembered I didn't fill the tank on that week. The conclusion is that the fuel was of bad quality. It shouldn't happen in Sweden, but I'v heard from others that it happens from time to time, but rarely.
Since then it has never ever happened again.

I was thinking that the fuel you are using could cause similar problems, but worse. But... no I don't think that is the reason why your engine stops.

But check the side stand sensor. Maybe it can be a intermittent related problem due to the sensor is 'bad'.

Have you checked for pinched/damaged wiring as suggested my Kev ?. You might have to disassemble the bike to inspect certain sections of the loom.

The only other thing I can suggest (that is easy) is to start isolating all non-essential electrical systems by removing the fuses (including ABS). Only keep the fuses essential to running the bike. See if this makes a difference.

The mechanics may have done all of the above, but we don't know.

It's looking like an electrics issue. If the mechanic got a shock, this is telling me shorted/damaged cabling. It's a matter of finding it.